https://github.com/westracer/flutter_native_opencv
Using OpenCV natively in C++ in a Flutter app with Dart FFI
https://github.com/westracer/flutter_native_opencv
android-ndk c dart-ffi flutter opencv-android
Last synced: 3 months ago
JSON representation
Using OpenCV natively in C++ in a Flutter app with Dart FFI
- Host: GitHub
- URL: https://github.com/westracer/flutter_native_opencv
- Owner: westracer
- License: mit
- Created: 2020-03-18T12:33:08.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2021-12-16T09:11:14.000Z (over 4 years ago)
- Last Synced: 2025-12-26T18:53:33.354Z (6 months ago)
- Topics: android-ndk, c, dart-ffi, flutter, opencv-android
- Language: C++
- Homepage: https://medium.com/flutter-community/integrating-c-library-in-a-flutter-app-using-dart-ffi-38a15e16bc14
- Size: 211 KB
- Stars: 218
- Watchers: 7
- Forks: 37
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# flutter_native_opencv
Using OpenCV natively in C++ in a Flutter app with Dart FFI. Tested with Flutter 2.5.2.
Read the full articles:
- Mobile platorms: https://medium.com/flutter-community/integrating-c-library-in-a-flutter-app-using-dart-ffi-38a15e16bc14
- Desktop platorms: https://medium.com/flutter-community/integrating-c-library-in-a-desktop-flutter-app-using-dart-ffi-32560cb1169b
# How to build & run
## Android and iOS
Run `init.sh` script from a `scripts` folder or do the following steps manually:
1. Download OpenCV for Android and iOS: https://opencv.org/releases/
2. Copy or create symlinks:
- `opencv2.framework` to `native_opencv/ios`
- `OpenCV-android-sdk/sdk/native/jni/include` to `native_opencv`
- Contents of `OpenCV-android-sdk/sdk/native/libs/**` to `native_opencv/android/src/main/jniLibs/**`
## Windows
Run `init_windows.ps1` PowerShell script from a `scripts` folder or do the following steps manually:
1. Download OpenCV for Windows: https://opencv.org/releases/
2. Unpack it. Set env. variable `OpenCV_DIR` to unpacked `...\opencv\build` folder
3. Create a hard link from `native_opencv\ios\Classes\native_opencv.cpp` to `native_opencv_windows\windows\native_opencv.cpp`
4. Make sure `native_opencv_windows\windows\CMakeLists.txt` contains correct .dll names (OpenCV_DEBUG_DLL_NAME,OpenCV_RELEASE_DLL_NAME)
## macOS
Before doing anything else, you need to download OpenCV source code and
build a framework by running `opencv/platforms/apple/build_xcframework.py` script.
Run `init_macos.sh` script from a `scripts` folder or do the following steps manually:
1. Create a hard link from `native_opencv/ios/Classes/native_opencv.cpp` to `native_opencv_macos/macos/Classes/native_opencv.cpp`
2. Copy `opencv2.xcframework` to `native_opencv/macos`
## Linux
Before doing anything else, you need to download OpenCV source code and
build libraries by following [the official tutorial](https://docs.opencv.org/master/d7/d9f/tutorial_linux_install.html).
After making a build, set up an environmental variable `OpenCV_DIR` to the build's folder.
Run `init_linux.sh` script from a `scripts` folder or do the following steps manually:
1. Create a hard link from `native_opencv/ios/Classes/native_opencv.cpp` to `native_opencv_linux/linux/native_opencv.cpp`
# Troubleshooting
```
/snap/flutter/current/usr/include/x86_64-linux-gnu/gnu/stubs.h:7:11: fatal error: 'gnu/stubs-32.h' file not found
# include
^~~~~~~~~~~~~~~~
1 error generated.
ninja: build stopped: subcommand failed.
```
or
```
/snap/flutter/current/usr/bin/ld: warning: /usr/lib/gcc/x86_64-linux-gnu/11/../../../x86_64-linux-gnu/crt1.o: unsupported GNU_PROPERTY_TYPE (5) type: 0xc0008002
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Exception: Build process failed
```
Install flutter manually instead of from snap, see: https://flutter.dev/docs/get-started/install/linux#install-flutter-manually